Preparation method of titanium alloy bar with high crystal orientation uniformity

Abstract

The invention belongs to the technical field of titanium alloy material processing, and particularly relates to a preparation method of a titanium alloy bar with high crystal orientation uniformity. Comprising the following steps that S1, one-upsetting and one-drawing cogging is conducted in a single-phase area, and remelting and heat preservation are conducted after forging; s2, one-upsetting and one-drawing forging is carried out on the two-phase region, and after upsetting, temperature compensation and drawing-out are carried out; s3, single-phase region heat preservation, and stage cooling after heat preservation; s4, multi-heating-number two-upsetting and two-drawing forging is conducted on the two-phase region, and reversing drawing-out is conducted after upsetting; s5, upsetting and drawing out the two-phase region; s6, drawing out a two-phase region; and S7, forming a two-phase region. The TC11 titanium alloy bar prepared through the process is good in structure and crystal orientation uniformity and has good mechanical performance after heat treatment, the difference of the mechanical performance of all areas is small, and the TC11 titanium alloy bar can be applied to aerospace high-end parts with strict requirements for the alloy structure and performance.

Description

Technical Field

[0001] This invention belongs to the field of titanium alloy material processing technology, specifically relating to a method for preparing titanium alloy rods with high crystal orientation uniformity. Background Technology

[0002] TC11 titanium alloy, an α+β type high-temperature titanium alloy widely used in the aerospace field, exhibits excellent high-temperature strength, creep resistance, and oxidation resistance at service temperatures around 500℃. It is primarily used in the manufacture of hot-end components such as integral bladed disks, casings, and drums for aero-engines. With the rapid development of the aerospace industry, the requirements for the microstructure and properties of these components are becoming increasingly stringent, especially regarding the uniformity of the alloy microstructure and the stability of its properties.

[0003] Thermomechanical processing is a primary manufacturing process for titanium alloys, but the inhomogeneity of microstructure and crystal orientation during processing remains a major challenge. While some progress has been made in optimizing the uniformity of alloy microstructure during industrial production in recent years, achieving a uniform distribution of crystal orientation is still not well resolved. In traditional forging processes, crystals in the alloy tend to undergo preferred orientation during hot deformation, forming strong deformation textures. During phase transformation, these textures are further influenced by variant selection, resulting in numerous microtextures. The presence of these textures and microtextures reduces the uniformity and coordination of alloy deformation, thus disrupting the uniformity of the alloy microstructure. Furthermore, it directly enhances the anisotropy of the alloy's mechanical properties, leading to a deterioration in fatigue performance and other mechanical properties, reducing the stability of mechanical properties and failing to meet practical application requirements.

[0004] Therefore, preparing large-size titanium alloy bars with uniform microstructure and crystal orientation and stable mechanical properties is a challenge that urgently needs to be addressed in the engineering field. It is necessary to further combine the evolution law and mechanism of alloy microstructure and crystal orientation during hot deformation process, and adjust and optimize the existing hot working process and parameters. Summary of the Invention

[0005] To address the aforementioned problems, this invention provides a forging process for large-size TC11 titanium alloy bars that can improve the uniformity of alloy microstructure and crystal orientation, and enhance the stability of alloy properties. Based on the evolution law and mechanism of microstructure and crystal orientation of TC11 alloy during hot deformation, this invention combines reversible upsetting deformation with multi-stage heat preservation, and further optimizes process parameters to achieve effective homogenization of the microstructure and crystal orientation of TC11 alloy during forging.

[0006] The technical solution adopted by this invention to solve its technical problem is a method for preparing titanium alloy rods with high crystal orientation uniformity, comprising the following steps:

[0007] S1. Heat the TC11 titanium alloy ingot to Tβ+(145~175)℃ and hold it at that temperature. After taking it out of the furnace, it is upsetting and drawing. The drawing operation is to first draw the upsetting ingot into a square shape and then into an octagonal shape. After drawing, it is returned to the furnace and held at Tβ+(10~20)℃. After the holding is completed, it is taken out of the furnace and air-cooled to obtain the first billet.

[0008] S2. Heat the first billet to Tβ-(50~10)℃ and hold it at that temperature. After taking it out of the furnace, it is upsetting. After upsetting, it is returned to the furnace to be heated to Tβ-(80~50)℃ and then drawn. The drawing operation is to first draw the first billet after upsetting into a square shape and then into an octagon shape. After drawing, the second billet is obtained.

[0009] S3. The hot material of the second billet is heated back into the furnace to Tβ+(20~50)℃ and held at that temperature. After the holding period, it is taken out of the furnace and air-cooled to Tβ-(20~10)℃ and then air-cooled to obtain the third billet.

[0010] S4. Heat the third billet to Tβ-(55~35)℃ and hold it at that temperature. After taking it out of the furnace, perform multiple forgings. Each forging includes two upsetting and two drawing operations. After one upsetting and drawing operation, reverse the direction of the third billet. The drawing operation is to first draw the square and then the octagon. Then air cool to obtain the fourth billet.

[0011] S5. Heat the fourth billet to Tβ-(50~30)℃ and hold it at that temperature. After taking it out of the furnace, it is upsetting. After upsetting, it is returned to the furnace to be heated to Tβ-(50~30)℃ and then drawn. The drawing operation is to draw the upsetting fourth billet into a square shape. After drawing, the fifth billet is obtained.

[0012] S6. Heat the fifth billet to Tβ-(50~30)℃ and hold it at that temperature. After taking it out of the furnace, stretch it to the target size, then put it back into the furnace and heat it to Tβ-(50~30)℃ and hold it at that temperature. After taking it out of the furnace, perform octagonal turning and round rolling to obtain the final billet.

[0013] S7. Heat the final billet from S6 to Tβ-(50~30)℃ and hold it thereafter. After air cooling, process it to the target diameter to obtain TC11 titanium alloy bar.

[0014] Furthermore, the initial holding coefficient of the ingot in S1 is 1.5~1.7 min / mm, and the holding time is not less than 900 min. During the heat preservation process in the furnace, the holding coefficient is 0.03~0.04 min / mm, the upsetting deformation is 55%~60%, and the deformation rate is 40~50 mm / s.

[0015] Furthermore, the thermal insulation coefficient of the first billet in S2 is 0.6~0.8 min / mm, the upsetting / drawing deformation during forging is 35%~40%, and the deformation rate is 15~20 mm / s.

[0016] Furthermore, the heat preservation coefficient of the second billet in S3 is 0.25~0.45 min / mm, and it is removed from the furnace in time after the heat preservation is completed.

[0017] Furthermore, in S4, the heat preservation coefficient before forging is 0.6~0.8 min / mm, the single upsetting deformation during forging is 50%, and the upsetting / drawing deformation rate is 10~15 mm / s.

[0018] Furthermore, in S4, the forging process involves no less than 3 forging passes, and the cumulative forging ratio is no less than 10.

[0019] The beneficial effects of this invention are:

[0020] 1. This invention effectively breaks down the coarse as-cast structure of the alloy by using a fast-rate large deformation billet in the S1 single-phase region, a slow-rate small deformation forging in the S2 two-phase region, and a heat preservation in the S3 single-phase region. By combining static recrystallization and dynamic recrystallization, and by taking advantage of the inhibitory effect of the precipitated α phase on the growth of β phase recrystallized grains, the original β phase grains of the alloy are fully refined and their crystal orientation is effectively dispersed. This is beneficial for obtaining a uniform and fine lamellar structure in the intermediate billet and avoids the formation of microtexture caused by the variant selection induced by coarse β phase grains and β deformation texture.

[0021] 2. The process of this invention combines S1, S2 and S3 to obtain an intermediate billet in which the fine, short rod-shaped lamellar α phase is uniformly distributed in the β phase matrix in the whole lamellar structure. At the same time, the crystal orientation distribution is uniform, which is conducive to the recrystallization and spheroidization of the lamellar α phase during subsequent forging. Combined with the slow-rate deformation in S4, it can further promote the formation of equiaxed α phase. At the same time, based on the uniform and fine whole lamellar structure combined with the reversal deformation in S4, the occurrence of preferred crystal orientation during forging can be effectively avoided, and the formation of texture and microtexture can be prevented.

[0022] 3. The TC11 titanium alloy bars prepared by the process of this invention exhibit an equiaxed microstructure in the high-magnification forged state, with excellent uniformity in microstructure and crystal orientation. Compared to traditional processes, the texture and microtexture are effectively eliminated. After heat treatment, the alloy bars possess excellent mechanical properties, with a room temperature tensile strength of not less than 1070 MPa and an elongation of not less than 16%. Simultaneously, the differences in mechanical properties across different regions of the bar are small, with the tensile strength difference between the head and tail not exceeding 10 MPa and the elongation difference not exceeding 1%. The TC11 titanium alloy bars prepared by the process of this invention meet the requirements of GJB 2218A-2018 "Specifications for Titanium and Titanium Alloy Bars and Forgings for Aerospace Use" and can be applied to high-end aerospace components with stringent requirements for alloy microstructure and performance. Attached Figure Description

[0023] Figure 1 High-magnification metallographic image of the cross-section of the TC11 titanium alloy bar (Φ600) prepared in Example 1 of this invention;

[0024] Figure 2 IPF diagram of the cross section of the TC11 titanium alloy bar (Φ600) prepared in Example 1 of the present invention;

[0025] Figure 3 The {0001}, {11-20}, and {10-10} pole figures are of the cross section of the TC11 titanium alloy bar (Φ600) prepared in Example 1 of the present invention.

[0026] Figure 4 This is a high-magnification metallographic image of the cross-section of a TC11 titanium alloy bar (Φ400) prepared in Example 2 of the present invention;

[0027] Figure 5 IPF diagram of the cross section of the TC11 titanium alloy bar (Φ400) prepared in Example 2 of the present invention;

[0028] Figure 6 The pole figures for the cross section of the TC11 titanium alloy bar (Φ400) prepared in Example 2 of this invention are {0001}, {11-20} and {10-10}. Detailed Implementation

[0029] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0030] like Figure 1 As shown, the present invention provides a method for preparing titanium alloy rods with high crystal orientation uniformity, comprising the following steps:

[0031] S1. Heat the TC11 titanium alloy ingot to Tβ+(145~175)℃ and hold it at that temperature. After taking it out of the furnace, perform upsetting and drawing. The drawing operation is to first draw the upsetting ingot into a square shape and then into an octagonal shape. After drawing, return it to the furnace and hold it at Tβ+(10~20)℃. After holding, take it out of the furnace and air cool it to obtain the first billet. The temperature and time of the holding stage after drawing need to be strictly controlled. The holding temperature of the holding stage is lower than the initial holding temperature to avoid the alloy grains growing due to excessive temperature. The holding temperature and time are the optimal parameters obtained through a large number of experiments, which make full use of static recrystallization to promote grain refinement.

[0032] S2. Heat the first billet to Tβ-(50~10)℃ and hold for a period of time. After removing it from the furnace, perform upsetting. After upsetting, return it to the furnace and reheat to Tβ-(80~50)℃ for drawing. The drawing operation involves first drawing the upset first billet into a square shape and then into an octagonal shape. After drawing, the second billet is obtained. Here, it is only necessary to reheat to Tβ-(80~50)℃. β -(80~50)℃, not Tβ -(50~10)℃, lowering the temperature of the heating can suppress grain growth and coarsening of the structure as much as possible, which is beneficial to obtaining fine and uniform full-lamellae structure in the future.

[0033] S3. The second billet is heated back to Tβ+(20~50)℃ and held at that temperature. After holding, it is removed from the furnace and air-cooled to Tβ-(20~10)℃ and then air-cooled to obtain the third billet. Rapid cooling above the phase transformation point prevents the original β crystals from continuing to grow, which is beneficial to obtaining fine and uniform full lamellar structure in the future.

[0034] S4. The third billet is heated to Tβ-(55~35)℃ and held at that temperature. After being taken out of the furnace, it is forged in multiple fires. Each fire forging includes two upsetting and two drawing operations. After one upsetting and drawing operation, the third billet is reversed. The drawing operation is to first draw the square and then the octagon. Then it is air-cooled to obtain the fourth billet. The "low-high" cyclic forging is beneficial to alleviate work hardening and promote the homogenization of the structure. Specifically, low temperature large deformation can effectively promote the recrystallization and spheroidization of the α phase and promote the homogenization of the structure. However, it will lead to work hardening and increase the deformation resistance. Therefore, the forging temperature needs to be increased in subsequent fires. Thus, the heating temperature in steps S5 and S6 is greater than the heating temperature in step S4.

[0035] S5. Heat the fourth billet to Tβ-(50~30)℃ and hold it at that temperature. In step S5, the holding time = holding coefficient × minimum thickness of the fourth billet. The holding coefficient is 0.6~0.8min / mm. After taking it out of the furnace, it is upsetting. After upsetting, it is returned to the furnace to be heated to Tβ-(50~30)℃ and then drawn. The drawing operation is to draw the upsetting fourth billet into a square shape. After drawing, the fifth billet is obtained.

[0036] S6. Heat the fifth billet to Tβ-(50~30)℃ and hold for a period of time. In step S6, the holding time = holding coefficient × minimum thickness of the fifth billet, and the holding coefficient is 0.6~0.8 min / mm. After removing it from the furnace, draw it to the target size, then reheat it in the furnace to Tβ-(50~30)℃ and hold for a period of time. After removing it from the furnace, perform octagonal shaping and round rolling to obtain the final billet.

[0037] S7. Heat the final billet from S6 to Tβ-(50~30)℃ and hold it at that temperature. After air cooling, process it to the target diameter to obtain TC11 titanium alloy bar.

[0038] Furthermore, in step S1, in the initial stage, the holding time = initial holding coefficient × minimum ingot thickness. The initial holding coefficient of the ingot in S1 is 1.5~1.7 min / mm, and the holding time is not less than 900 min, to ensure that the alloy is fully heated and the ingot is fully homogenized. In the furnace holding stage, the holding time = holding coefficient × minimum ingot thickness after upsetting. The holding coefficient during the furnace holding process is 0.03~0.04 min / mm, to refine the grains by utilizing the static recrystallization of the alloy. In step S1, the upsetting deformation is 55%~60%, and the deformation rate is 40~50 mm / s, to fully break the as-cast structure through rapid high-rate deformation.

[0039] Furthermore, in step S2, the holding time = holding coefficient × minimum thickness of the first billet. In S2, the holding coefficient of the first billet is 0.6~0.8 min / mm. During forging, the upsetting / drawing deformation is 35%~40%, and the deformation rate is 15~20 mm / s. The holding coefficient of 0.6~0.8 min / mm ensures sufficient fluidity of the alloy during deformation; the deformation during upsetting / drawing is 35%~40%, and the deformation rate is 15~20 mm / s. Using a slow rate and small deformation avoids significant temperature rise in the alloy.

[0040] Furthermore, in step S3, the holding time = holding coefficient × minimum thickness of the second billet. The holding coefficient of the second billet in S3 is 0.25~0.45 min / mm. The billet is removed from the furnace promptly after the holding period. This prevents excessive grain growth and facilitates obtaining a uniform and fine lamellar microstructure.

[0041] Furthermore, in step S4, the holding time = holding coefficient × minimum thickness of the third billet. In S4, the holding coefficient before forging is 0.6~0.8 min / mm, the single upsetting deformation during forging is 50%, and the upsetting / drawing deformation rate is 10~15 mm / s. The holding coefficient of 0.6~0.8 min / mm ensures sufficient fluidity of the alloy during deformation; the single upsetting deformation during the upsetting process is 50%, and the upsetting / drawing deformation rate is 10~15 mm / s, using slow-rate deformation to promote full dynamic recrystallization of the alloy.

[0042] Furthermore, in S4, the forging process involves no fewer than three forging passes, with a cumulative forging ratio of no less than 10. This ensures sufficient equiaxing of the lamellar α phase and improves the uniformity of the microstructure.

[0043] Example 1

[0044] This embodiment includes the following steps:

[0045] S1. Heat the TC11 titanium alloy ingot (ingot specifications: Φ600×2060mm, weight: 2608 kg, phase transformation point: 995℃) to 1140℃ and hold for 1020 min. Then, perform billet preparation in the single-phase zone, with one upsetting and one drawing. The upsetting operation is bar stock (Φ600×2060) → bar stock (ΦD×820). After upsetting, return the bar stock to the furnace and hold at 1005℃ for 30 min. Then, draw the bar stock out of the furnace. The operation is bar stock (ΦD×820) → square (710×L) → octagonal (750×1361). The upsetting rate is 40 mm / s and the upsetting deformation is 60%. After forging, air cool.

[0046] S2. The alloy billet obtained in S1 is held at 945℃ for 600 min, and then forged. The process involves one upsetting and one drawing. The upsetting operation is octagonal (750×1361) → octagonal (D×880). After upsetting, the billet is returned to the furnace to be heated to 915℃, and then drawn. The operation is octagonal (D×880) → square (710×L) → octagonal (750×1361). The upsetting rate is 15 mm / s, the drawing rate is 20 mm / s, the upsetting deformation is 40%, and the drawing deformation is 35%.

[0047] S3. Return the hot alloy billet obtained in S2 to the furnace and hold it at 1015℃ for 335 minutes. Then, remove it from the furnace and air-cool it to 975℃ and continue air cooling.

[0048] S4. The alloy billet obtained in S3 is held at 940℃ for 600 min, then taken out of the furnace for forging, with a total of two upsetting and two drawing operations. The first upsetting and drawing operation is octagonal (750×1361) → octagonal (D×680) → tetragonal (710×L) → octagonal (750×1361). Then it is put back into the furnace for holding for 225 min. After taking out of the furnace, the direction is reversed for the second upsetting and drawing operation, which is octagonal (750×1361) → octagonal (D×680) → tetragonal (710×L) → octagonal (750×1361). The upsetting rate is 14 mm / s, the drawing rate is 20 mm / s, and the single upsetting deformation is 50%. After forging, it is air-cooled.

[0049] S41: Repeat operation S4, with the upsetting rate adjusted to 12 mm / s;

[0050] S42: Repeat operation S4, with the upsetting rate adjusted to 10 mm / s;

[0051] S5. The alloy billet obtained in step S42 is held at 945℃ for 600 min. The upsetting operation is octagonal (750×1361) → octagonal (D×680), and the drawing operation is octagonal (D×680) → tetragonal (710×L). The upsetting rate is 14 mm / s, the drawing rate is 20 mm / s, the upsetting deformation is 50%, and the billet is air-cooled after forging.

[0052] S6. Hold the alloy billet obtained in step S5 at 945℃ for 600 min, and draw it from square (710×L) to square (630×L) at a rate of 20 mm / s. After drawing, hold the alloy billet at 945℃ for 600 min and then remove it from the furnace. Then, turn it into an octagon and roll it into a round shape. The specific operation is from square (630×L) to octagon (640×L) to bar (Φ630×L). After the operation, air cool it.

[0053] S7. Hold the alloy billet obtained in step S5 at 945℃ for 600 min, roll it into a bar (Φ615×L), air cool it, and machine it to size (Φ600×L). The surface roughness Ra≤3.2 μm is used to obtain a Φ600 TC11 titanium alloy bar.

[0054] Microstructural characterization of the TC11 alloy rods prepared in this embodiment revealed that the high-magnification forged titanium microstructure is equiaxed, with the equiaxed α phase uniformly distributed within the β phase matrix. Figure 1 As shown. Further crystal orientation analysis revealed a uniform distribution of crystal orientations within the microstructure, with no microtexture observed. Figure 2 As shown; the maximum texture intensity of the pole figure is only 1.95, which can be considered as no texture being produced, such as Figure 3 As shown.

[0055] Example 2

[0056] This embodiment includes the following steps:

[0057] S1. Heat the TC11 titanium alloy ingot (ingot specifications: Φ650×1848 mm, weight: 2844 kg, phase transformation point: 995℃) to 1170℃ and hold for 975 min. Then, perform billet preparation in the single-phase zone, with one upsetting and one drawing. The upsetting operation is bar stock (Φ600×1848) → bar stock (ΦD×830). After upsetting, return the bar stock to the furnace and hold at 1015℃ for 20 min. Then, draw the bar stock out of the furnace. The operation is bar stock (ΦD×830) → square (710×L) → octagonal (750×1361). The upsetting rate is 50 mm / s and the upsetting deformation is 55%. After forging, air cool.

[0058] S2. The alloy billet obtained in S1 is held at 985℃ for 450 min, and then forged. The process involves one upsetting and one drawing. The upsetting operation is octagonal (750×1361) → octagonal (D×880). After upsetting, the billet is returned to the furnace to be heated to 945℃, and then drawn. The drawing operation is octagonal (D×880) → square (710×L) → octagonal (750×1361). The upsetting rate is 15 mm / s, the drawing rate is 20 mm / s, the upsetting deformation is 40%, and the drawing deformation is 35%.

[0059] S3. The hot alloy billet obtained in S2 is returned to the furnace and held at 1045℃ for 190 min. Then it is taken out of the furnace and air-cooled to 985℃ and then air-cooled again.

[0060] S4. The alloy billet obtained in S3 is held at 960℃ for 450 min, then removed from the furnace and forged, involving two upsetting and two drawing operations. The first upsetting and drawing operation is as follows: octagonal (750×1361) → octagonal (D×680) → tetragonal (710×L) → octagonal (750×1361). After that, it is held in the furnace for 185 min, and then the direction is reversed for the second upsetting and drawing operation, which is as follows: octagonal (750×1361) → octagonal (D×680) → tetragonal (710×L) → octagonal (750×1361). The upsetting rate is 14 mm / s, the drawing rate is 20 mm / s, and the upsetting deformation is 50%.

[0061] S41. Using the alloy billet obtained in S4, repeat the S4 operation, wherein the upsetting rate is adjusted to 12 mm / s.

[0062] S42. Using the alloy billet obtained in S41, repeat the S4 operation, wherein the upsetting rate is adjusted to 10 mm / s.

[0063] S43. Using the alloy billet obtained in S42, repeat the S4 operation, wherein the upsetting rate is adjusted to 10 mm / s.

[0064] S5. The alloy billet obtained in S43 is held at 965℃ for 450 min. After being taken out of the furnace, it is upsetting and drawing. The upsetting operation is octagonal (750×1361) → octagonal (D×680), and the drawing operation is octagonal (D×680) → square (710×L). The upsetting rate is 14 mm / s, the drawing rate is 20 mm / s, and the single upsetting deformation is 50%. After forging, it is air-cooled.

[0065] S6. Hold the alloy billet obtained in step S5 at 965℃ for 450 min, then draw it out of the furnace. The drawing operation is from square (710×L) to square (620×L). Then, it is held in the furnace for 125 min and drawn out again from square (620×L) to square (500×L). Then, it is held in the furnace for 125 min and drawn out to the target size from square (500×L) to square (430×L). The drawing rate is 20 mm / s.

[0066] S61. The alloy billet obtained in step S6 is held at 965℃ for 450 min. After being taken out of the furnace, it is turned into an octagon and rolled into a round shape. The specific operation is as follows: square (430×L) → octagon (440×L) → bar (Φ430×L). After the operation is completed, it is air-cooled.

[0067] S7. The alloy billet obtained in step S61 is held at 965℃ for 450 min, rolled to Φ415×L, air-cooled, and machined to Φ600×L with a surface roughness Ra≤3.2 μm to obtain Φ400 TC11 titanium alloy bar.

[0068] Microstructural characterization of the TC11 alloy rods prepared in this embodiment revealed that the high-magnification forged titanium microstructure is equiaxed, with the equiaxed α phase uniformly distributed within the β phase matrix. Figure 4 As shown. Further crystal orientation analysis revealed a uniform distribution of crystal orientations within the microstructure, with no microtexture observed. Figure 5 As shown; the maximum texture intensity of the pole figure is only 1.87, which can be considered as no texture being produced, such as Figure 6 As shown.

[0069] The TC11 alloy bars prepared in Examples 1 and 2 were subjected to solution aging treatment and their properties were characterized as shown in Table 1. It can be found that the room temperature tensile strength of the above bars is not less than 1070 MPa, the yield strength is not less than 980 MPa, the elongation is not less than 16%, the reduction of area is not less than 40%, the difference in tensile strength between the head and tail is not more than 10 MPa, and the difference in elongation is not more than 1%.

[0070] Mechanical properties of solution-aged TC11 alloy bars

[0071]

[0072] The table above shows that the TC11 alloy rods prepared by this invention have good microstructure and crystal orientation uniformity, with no texture or microtexture, and the alloy rods have good strength and plasticity matching, with small differences in mechanical properties in different regions, which meets the requirements of GJB 2218A-2018 "Specifications for Titanium and Titanium Alloy Rods and Forgings for Aviation".

[0073] The embodiments described herein are preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Therefore, all equivalent changes made in accordance with the structure, shape, and principle of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A method for preparing titanium alloy rods with high crystal orientation uniformity, characterized in that, Includes the following steps: S1. Heat the TC11 titanium alloy ingot to Tβ+(145~175)℃ and hold it at that temperature. After taking it out of the furnace, it is upsetting and drawing. The drawing operation is to first draw the upsetting ingot into a square shape and then into an octagonal shape. After drawing, it is returned to the furnace and held at Tβ+(10~20)℃. After the holding is completed, it is taken out of the furnace and air-cooled to obtain the first billet. S2. Heat the first billet to Tβ-(50~10)℃ and hold it at that temperature. After taking it out of the furnace, it is upsetting. After upsetting, it is returned to the furnace to be heated to Tβ-(80~50)℃ and then drawn. The drawing operation is to first draw the first billet after upsetting into a square shape and then into an octagon shape. After drawing, the second billet is obtained. S3. The hot material of the second billet is heated back into the furnace to Tβ+(20~50)℃ and held at that temperature. After the holding period, it is taken out of the furnace and air-cooled to Tβ-(20~10)℃ and then air-cooled to obtain the third billet. S4. Heat the third billet to Tβ-(55~35)℃ and hold it at that temperature. After taking it out of the furnace, perform multiple forgings. Each forging includes two upsetting and two drawing operations. After one upsetting and drawing operation, reverse the direction of the third billet. The drawing operation is to first draw the square and then the octagon. Then air cool to obtain the fourth billet. S5. Heat the fourth billet to Tβ-(50~30)℃ and hold it at that temperature. After taking it out of the furnace, it is upsetting. After upsetting, it is returned to the furnace to be heated to Tβ-(50~30)℃ and then drawn. The drawing operation is to draw the upsetting fourth billet into a square shape. After drawing, the fifth billet is obtained. S6. Heat the fifth billet to Tβ-(50~30)℃ and hold it at that temperature. After taking it out of the furnace, stretch it to the target size, then put it back into the furnace and heat it to Tβ-(50~30)℃ and hold it at that temperature. After taking it out of the furnace, make it into an octagon and roll it into a round shape to obtain the final billet. S7. Heat the final billet from S6 to Tβ-(50~30)℃ and hold it at that temperature. After air cooling, process it to the target diameter to obtain TC11 titanium alloy bar.

2. The method for preparing titanium alloy rods with high crystal orientation uniformity according to claim 1, characterized in that: The initial holding coefficient of the ingot in S1 is 1.5~1.7 min / mm, and the holding time is not less than 900 min. During the heat preservation process in the furnace, the holding coefficient is 0.03~0.04 min / mm, the upsetting deformation is 55%~60%, and the deformation rate is 40~50 mm / s.

3. The method for preparing titanium alloy rods with high crystal orientation uniformity according to claim 1, characterized in that: The thermal insulation coefficient of the first billet in S2 is 0.6~0.8 min / mm, the upsetting / drawing deformation during forging is 35%~40%, and the deformation rate is 15~20 mm / s.

4. The method for preparing titanium alloy rods with high crystal orientation uniformity according to claim 1, characterized in that: The heat preservation coefficient of the second billet in S3 is 0.25~0.45 min / mm, and it should be removed from the furnace in time after the heat preservation is completed.

5. The method for preparing TC11 titanium alloy rods with high crystal orientation uniformity according to claim 1, characterized in that: The heat preservation coefficient before forging in S4 is 0.6~0.8 min / mm, the single upsetting deformation during forging is 50%, and the upsetting / drawing deformation rate is 10~15 mm / s.

6. The method for preparing titanium alloy rods with high crystal orientation uniformity according to claim 1, characterized in that: In S4, the forging process involves no less than 3 forging passes, and the cumulative forging ratio is no less than 10.

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